Skype is a great technology. It is incredibly cheap for calling plans (to anywhere in the world, I believe), and the chat and video functions are free to use once you have signed up for the service (I believe you can even host group conferencing, up to a limited number of people).

Here are a couple of possible uses, off the top of my head:

Example 1: Using Skype for administration and/or departmental meetings with travelling or distant online faculty.

Example 2: Using it for small classes, especially for tutorials.

Example 3: Using a Skype plan on an iPod touch to make a limited use iPhone (for a fraction of the cost).

Pros: easy to use -- sign up is easy; chat/video functions are free; cheap phone plans for those constantly on the move

Cons: need to be tied to a computer and/or device capable of wireless and/or high speed connections (i.e. you can't take this technology anywhere, like a cell phone and 3G (if I am using this latter term correctly)); the audio quality, while generally good, is susceptible to dropouts. This is even more true about video connection, whcih is sometimes hard to establish, but there is always a reserve written real-time communication mode.